Stringed musical instruments that contain electrical pickups commonly also include a volume and possibly a tone control. Such self-contained controls allow the performer him or her self to alter the level and quality of the performance while it is taking place. The controls usually take the form of a potentiometer connected between the pickup and the amplifier input. In the case of a tone control, a capacitor is usually also included. One problem that exists is that the pickups, be they magnetic or piezo crystal, have a relatively high impedance, and the control potentiometers present a significant load to the pickup, limiting the maximum volume and frequency response attainable. It is possible to switch a potentiometer out of the circuit when more volume and full frequency response is desired, but auxiliary switches are not convenient, and ordinary switches are generally of the “snap action” type and so create an undesired sound in the amplified signal (partly because of mechanical coupling).